Auf questions. Don’t have it. Wonder if I need it

[Milbags]

I have a 2x5 evaporator with a hood and we are boiling about 7-8 gallons per hr . With no preheat. I’ve now added a hood and copper pipe in the hood for a pre heater. I’m wondering how would I add the auf and also what time of fan would I buy if I don’t have power In my shack.

[maple flats]

If you have no power and do not have a generator (or prefer the quiet) try raising the height of the stack. Generally 10' would be used, but 12' or 14' will increase the air flow to make it burn hotter and no genny noise.

[NhShaun]

If you feel like investing in a small solar set up you could run a 12v blower fan. I picked one up that was used in a giant green house between the two sheets of plastic. It's only like 140cfm but it runs off my 100ah battery for the whole evening of boiling and is ready to go again by the time I get back to boil the next day. (Weather permitting) it's a a little cheaper than a generator, a lot quieter and it's just more green. Not sure how much more efficient it made my evaporator, but you can sure hear the difference in the firebox when the blower is going.

[mol1jb]

I dont know if you need one but many people have added AUF and after the difference they saw they will never go back. Figuring how to run one on with out power will be your biggest hurdle but others have made some good suggestions.

[Big_Eddy]

I have a 2x5 evaporator with a hood and we are boiling about 7-8 gallons per hr . With no preheat. I’ve now added a hood and copper pipe in the hood for a pre heater. I’m wondering how would I add the auf and also what time of fan would I buy if I don’t have power In my shack.

Lots of variables. A 2x5 can do a lot better than 7-8 gallons an hour even on natural draft.
Is this a flat pan, or do you have a flue pan?
What size wood are you burning, how dry is it, how often are you firing?
How much stack do you have and what size?

I would expect a 2x5 flat pan, with 10' of 7" or 8" pipe, fired every 8 mins with dry wood no larger than 4" in any dimension (except length!) to achieve 10gph easily.
With a flue pan, somewhere in the range of 15-25gph.

However, if you're firing the same evaporator every 15 mins with "stove wood", then 7-8 gph would be typical.

Adding AUF will increase both the boil rate and wood consumption. Anecdotally, it can double throughput without any other changes.

[Sugarmaker]

I was thinking the same thing as Big Eddy. I would look to improve the boiling rate prior to adding any thing. A new local sugarmaker (Scott R.) is boiling on a 2 x 6 (with a AUF) at 50 gallon per hour. I would think with natural draft you should be at 25-30 gph??
Thinks like stack height and features, wood type, size and dryness can be factors. Cold sap being added can slow down the boil too.
Regards,
Chris

[Chickenman]

just get a stationary bike to power a fan using a belt. Open it up at a fitness center and people will pay you to run it. lol

[Milbags]

As of now I have a custom setup. I got a wood stove and cut the back off and extended it with a 6 inch c Chanel and then tapered the ramp from 3.5 to 1 inch. I did boil with no preheated and worked good. I’ve not got the hood done and got copper pipe in their to preheat the sap. But I don’t think it’s gonna get me 20 gph Any suggestions. I’d love to put a picture in this thread but have no clue how to do that. Could I email it to someone

[maple flats]

You say the back part tapers from 3.5" it 1", do you have it insulated to finish at that space or is it just the bottom getting closer to the pan?
You can email me a picture or pictures to: dave@cnymaple.com I will look at them within one day (busy time of year).
You say you cut the back off for making the extension, does you pan set just on 1/4-3/4" ledge and the rest is all open to the heat? If part is setting on the original stove top you will loose too much of the potential heat transfer.

[Sugarmaker]

Also, if this is a flat pan with no flues you mileage is going to vary a lot.
Regards,
Chris